With the prior art, services for audio conferences are part of the essential range of services offered by voice switching networks. They are provided by the switching centers of the network or even by network elements external to the switching centers. The conference function here is based on a combined function for the audio stream of the participating conferees, which is provided by a specific hardware unit with DSP capacity (Digital Signal Processor).
In conventional cases, where the useful channel of a connection is fed to the switching center, the conference functions and the announcement and tone functions required for these can be provided by peripheral devices or external devices equipped with corresponding functionality. If, however, the useful data is conveyed outside the switching center in a packet network, preferably at least one external conference system is used for this. The system has interfaces with the packet network for the useful data of the conference. The useful data of the conference here is either the useful data of the individual conferees or the announcements/dialogs and tones to be input as well as the combined signal to be distributed to the conferees, which is generated via at least one conference bridge. The external conference system can also have a control interface with the switching center controlling connections in the packet network conveyed outside the switching center, in order to control the required basic functions during the conference or to initiate the interspersion of announcements/dialogs and tones generated in the external conference system for example.
Essentially conference services have a range of conference features, which can be differentiated and defined in respect of the initiation and control of the progress of the conference:
There are on the one hand conference features, with which users are included as participants by DIAL-IN (dialing of the conferee into the conference) or by DIAL-OUT (calling of the conferee out of the conference), i.e. the conference process is characterized by the availability of the conferees (e.g. by connecting participants to the conference or the departure of participants from the conference).
On the other hand, there are conference features which are characterized by the conference leader or the conferees of the controlled conferences. For example, conferees can be connected, switched to silent or disconnected from the conference by a conference leader by means of appropriate DSS1 signaling (ETSI ADD-ON conference) or via an additional graphic control system on a PC-type terminal. These conference features controlling the conference are often available to the Conference Service Operator, who can manage the conference resources in the network and monitor the conference service.
With regard to videoconferences, which are increasingly used in packet-based networks, the need for conference control is increased by the participating conferees, who increasingly wish to influence the image to be viewed. This includes the selection of one or more participants during the conference, voice-activated switching of the image to the conferees speaking at the time, simultaneous image availability for a certain number of conferees and the additional insertion of documents.
Conversely, existing conference solutions inform the participants currently in a conference about the inclusion of a further conferee in the conference or the fact that a conferee has left the conference by means of conference tones and/or by means of generally few conference announcements of corresponding content.
With regard to the initiation and control of conferences, the following distinction is made between conference services:
With the ETSI-ADD-ON conference, control is by definition only possible in a local switching center. It is initiated and controlled via conferee signaling (numerical sequence control). It is primarily available in TDM-based but also in packet-based networks, the switching centers of which support conventional participant signaling and can be initiated directly (AD HOC).
The PRESET conference represents a compromise between AD HOC initiation and a simultaneously predefined conferee list.
The PHONEMEET conference is offered as a general network service (public conference). This service, which is very similar to the internet chat service but is much longer established, provides a Service Code, which can be used to dial into a conference on a specific topic and have discussions with conferees who have already dialed into the topic. Conferees do not generally identify themselves and have no guarantee that they will be connected to a repeat joint conference when they dial in again. The characterizing feature of such a service is that participants, who generally do not know each other, can have discussions in the public network. No control by conferees is required, and automatic monitoring of disruptive parties is not available. Some network operators have operators to monitor conference availability and the undisrupted progress of the conference, the operators identifying and isolating hostile disruptive parties by sporadically listening in.
Pre-reserved conferences are available as DIAL-IN, DIAL-OUT or MIXED DIAL-IN/DIAL-OUT conferences. They are particularly useful for business customers. One disadvantage is that pre-reservation and conference planning have to be carried out manually and there is therefore no AD HOC availability.
For the purposes of completeness, reference should be made to conference services with Web-based operator interfaces (such as Siemens SURPASS WEBCONFER) and TERMINAL conferences, which are supported according to certain signaling standards. The former can be booked and controlled via internet access. The advantage of Web-based control with Status Display is limited by the disadvantage of internet access with the possible requirement of an additional terminal for the conference leader and lack of interaction with the conferees. TERMINAL conferences are for example conferences for audio, video and data, which depend on the terminal functions and are possible with the specifications of the H.323 Standard (or even the SIP Standard), with which conventional terminals cannot be used. A central bridge is superfluous here. Major conferences with a large number of participants are however not possible due to the limited performance of the terminals. A further disadvantage is the increased bandwidth requirement between conferees.
Resources have to be made available in the network for all conference services. As conference services represent a cost-intensive investment for network operators, they are not made available to an unlimited degree in the network. This means increased control costs; for as well as the interactions between the conference leader and the participants during the conference, the time and date of the conference have to be agreed, the availability of the conferees and the appropriate conference resources has to be established and participants have to be informed of the time and access authorization, to ensure the success of the conference.
Conferences which can be initiated on an AD HOC basis from experience have a control interface characterized by numerical sequence control of the telephony or a graphic control interface connected to a higher quality, intelligent, possibly additional, terminal, which set the limits for the sporadically immediate operability of any terminal. The system tones and announcements made available to the conferees only allow general conclusions about the progress and status of the conference. As far as pre-reserved conferences are concerned, in some circumstances significant manual interaction is required before the start of the conference. Such impediments make the deployment, use and success of conference solutions problematic.